Effluent Phosphorus Concentration Research Articles

Intensive Microalgal Cultivation and Tertiary Phosphorus Recovery from Wastewaters via the EcoRecover Process.

Mixed community microalgal wastewater treatment technologies have the potential to advance the limits of technology for biological nutrient recovery while producing a renewable carbon feedstock, but a deeper understanding of their performance is required for system optimization and control. In this study, we characterized the performance of a 568 m3·day-1 Clearas EcoRecover system for tertiary phosphorus removal (and recovery as biomass) at an operating water resource recovery facility (WRRF). The process consists of a (dark) mix tank, photobioreactors (PBRs), and a membrane tank with ultrafiltration membranes for the separation of hydraulic and solids residence times. Through continuous online monitoring, long-term on-site monitoring, and on-site batch experiments, we demonstrate (i) the importance of carbohydrate storage in PBRs to support phosphorus uptake under dark conditions in the mix tank and (ii) the potential for polyphosphate accumulation in the mixed algal communities. Over a 3-month winter period with limited outside influences (e.g., no major upstream process changes), the effluent total phosphorus (TP) concentration was 0.03 ± 0.03 mg-P·L-1 (0.01 ± 0.02 mg-P·L-1 orthophosphate). Core microbial community taxa included Chlorella spp., Scenedesmus spp., and Monoraphidium spp., and key indicators of stable performance included near-neutral pH, sufficient alkalinity, and a diel rhythm in dissolved oxygen.

Fe(II)-driven spatiotemporal assembly of heterotrophic and anammox bacteria enhances simultaneous nitrogen and phosphorus removal for low-strength municipal wastewater

The mainstream anaerobic ammonium oxidation (anammox) faces considerable challenges with low-strength municipal wastewater. A Fe(Ⅱ)-amended partial denitrification coupled anammox (PD/A) process was conducted and achieved a long-term and efficient nitrogen and phosphorus removal, yielding effluent total nitrogen and phosphorus concentrations of 1.97 ± 1.03 mg/L and 0.23 ± 0.13 mg/L, respectively, which could well meet more stringent effluent discharge standard of some wastewater treatment plants in specific geographical locations, e.g., estuaries. Fe(Ⅱ)-driven vivianite formation provided key nucleuses for the optimization of the spatial distribution of heterotrophic and anammox bacteria with enhanced extracellular polymeric substances as key driving forces. Metagenomics analysis further revealed the increase of key genes, enhancing anammox bacteria homeostasis, which also bolstered the resistance to environmental perturbations. This study provided a comprehensive sight into the function of Fe(Ⅱ) in mainstream PD/A process, and explored a promising alternative for synergetic nitrogen and phosphorus removal for low-strength municipal wastewater treatment.

Reactive media constructed wetland for phosphorus removal: assessing the opportunity and challenges

ABSTRACT Reactive media present an alternative to gravel in constructed wetlands and have the potential to sustainably and efficiently remove phosphorus from wastewater. In this study, a full-scale steel slag wetland has been operated for its whole lifecycle at which 1.39 mg P/g media were retained. During its lifecycle, this wetland met strict consents below 0.5 mg P/L for the first 6 months and was operated for 266 and 353 days before the effluent phosphorus concentration rose above the typical consents of 1 and 2 mg P/L, respectively. A detailed analysis of the system demonstrated that the performance was directly associated with the release of materials from the media into the water which in turn affected other critical parameters such as pH. Further analysis of the media suggested that greater understanding was needed concerning the role of carbonates and in particular calcite if steel slag is to be effectively managed for use on constructed wetlands. Importantly, controlled release of calcium oxide from the media surface is required by managing the concerns of pH and vanadium release.

Full nitrogen and phosphorus removal in the PASDEBPR system

Photo-activated sludge (PAS) system aims to utilize microalgae to deliver oxygen for bacterial respiration, eliminating the need for external aeration. However, research on the treatment potential of PAS systems in the removal of nutrients is limited. In this context, a research study was devised to evaluate the possibility of developing a microalgae-bacteria consortium to achieve the simultaneous removal of organic carbon, nitrogen, and phosphorus. A successful PAS system capable of removing phosphorus was established at the end of the first phase, with an effluent phosphorus (P) concentration of 1.6 mg P L−1. In the subsequent stage, during the introduction of the nitrification-denitrification process, the system lost stability and deteriorated. Interestingly the system recovered via the sparging of nitrogen gas reaching effluent concentrations of 1.22 mg P L−1 and 0.88 mg N L−1. Thus, the system was capable of removing phosphorus and nitrogen via biological means without the need for external aeration. It is hypothesized that the inhibition caused was due to the production of a gaseous compound during the nitrification/denitrification process.

Simulation assisted process simplification and energy recovery from a cryptic biological nutrient removal plant

In this study, simulation-based analysis is conducted for nitrogen removal mechanism in a biological nutrient removal plant designed in an encrypted manner. In the first phase, the simulation study elucidates how nitrogen removal occurs in a complex design using a series of 4 carousel bioreactors with additional nitrate recycle. It is demonstrated that pre-anoxic volume fed with limited internal recirculation only would not be sufficient to meet the discharge Total Nitrogen (TN) limit of 10 mg N/L. However, the addition of simultaneous nitrification-denitrification (SND) processes in aerobic reactors enables compliance with TN discharge limits. In the second phase, the configuration is simplified by means of process simulation, where the complex design is streamlined by eliminating internal recycle while achieving nitrogen removal through the SND process. Plant data confirmed that the simplified configuration can achieve nitrogen removal providing the same discharge quality. The simulations resulted that TN concentration achieved at the plant effluent is comparable, while effluent total phosphorus concentration is decreased by approximately 50 % due to increased activity of Phosphorus Accumulating Organisms (PAOs) under reduced sludge retention time (SRT). In the third phase, the application of the SND process in the field using a simplified and new activated sludge configuration yields similar results to the simulation. According to plant records, 28 % energy savings and an equivalent chemical cost reduction of €945,000 per year were achieved with the new process configuration.

Techno-economic analysis of a circular microalgal approach for enhanced wastewater treatment and resource recovery in Northern Portugal

Microalgae culturing in municipal wastewater treatment plants (WWTP) can be a solution to lower the effluent's nitrogen and phosphorus concentrations to comply with the new legislative limits. Microalgae can also promote a circular approach to WWTP by recycling material streams and reducing the energetic consumption of the treatment process. This study aims to perform a techno-economic assessment of the integration of microalgae culture (Chlorella vulgaris) as tertiary treatment at a WWTP in northern Portugal. This evaluation took into account information collected from the specific WWTP under study as well as relevant literature for each stage of the process. The major system flows: (i) a 7377 m3 d−1 treated water flow (ii) the treatment of 107,736 kg d −1 of sludge; (iii) a biosolids soil amendment production of 7580 kg d−1; and (iv) 10,874 kW h d−1 energy for self-consumption. In this work, the integration of microalgae in WWTP achieved yearly gross earnings of approximately 619,100 €.

Investigating the applicability of waste foam concrete for phosphorus recovery in real pig wastewater based on the effect of organic matter on the HAP crystallisation method

HAP crystallization use waste foam concrete as a calcium source, studied the impact of typical organic compounds in simulated pig wastewater on phosphorus recovery, and applied them to actual wastewater. Energy dispersive X-ray spectrometer(EDS) and SEM indicate: citric acid had a stronger inhibitory effect on crystallization compared to humic acid. Citric acid chelated Ca2+ ions, competing with crystallization ions and interfering with crystal nucleation. Humic acid hindered crystal growth through adsorption and ion exchange mechanisms. When citric acid and humic acid were added together, they competitively interacted, reducing the inhibition of phosphorus recovery. HAP crystallization alone reduced phosphorus content and turbidity in secondary pig wastewater, while combining 2 mL(5 g/L)PAM yielded favorable outcomes. Effluent phosphorus concentration was only 1.0 mg/L, with turbidity below 25. here was a noticeable reduction in Pseudomonas pathogenic bacteria from the Aspergillus phylum, along with a significant downward trend in the CL500_29_marine_group, which represents water body eutrophication. The combined method cost RMB 1.15 yuan/ton of water treated, a 26 % decrease compared to the original treatment plant. This method is suitable as an add-on unit for secondary pig wastewater treatment.

Process intensification of chemical phosphorus removal in a microreaction system

Serious problems including excessive ferric salt dose, high effluent phosphorus concentration and long handling time are encountered for chemical phosphorus removal by ferric salt in batch processes due to poor mixing performance. In this work, we develop a microreaction system to intensify phosphorus removal process using ferric chloride by achieving rapid mixing. Phosphorus residual is remarkably reduced by optimizing mixing-related factors, including flow rate, contacting mode, device structures and flow rate ratio which is justified by CFD simulation. The results show that phosphorus removal performance is not sensitive to flow rate ratio. Phosphorus residual can be lower than 0.20 mg/L at [P]0 = 6 mg/L, pH = 6.0, Fe/P = 1.8 and residence time = 42.8 s. Compared with batch processes, the microreaction system has several advantages including much lower phosphorus residual, lower ferric salt dose, shorter processing time and larger handling capacity. Moreover, a machine learning model is established to predict the device performance with high accuracy.

Performance and mechanism of phosphorus adsorption removal from wastewater by a Ce-Zr-Al composite adsorbent.

With the increasingly serious eutrophication of global water bodies and the strict discharge standards of tail water in wastewater treatment plants (WWTPs), there is an urgent technology need for efficient deep phosphorus removal from wastewater. A composite cerium-based adsorbent (Ce-Zr-Al) was synthesized by coprecipitation method for the adsorption of low concentration phosphorus in water. The performance of the Ce-Zr-Al composite adsorbent was explored, and the mechanism was also revealed through the analyses including SEM, BET, XPS, and FT-IR. The results showed that the composite adsorbent had excellent phosphorus removal performance. The phosphorus removal rate reached up to 92.6%, and the phosphorus concentration in effluent was less than 0.074 mg/L. The phosphate adsorption capacity of saturation was 73.51 mg/g. The adsorption process of phosphate was in accordance with pseudo-second-order kinetic model and Langmuir model. In addition, the composite adsorbent had a high zero potential point (pH PZC= 8) and a wide range of pH application. After the repeated desorption for 10 times in NaOH solution, the composite adsorbent still maintained good adsorbability (adsorption rate > 94%). The ligand exchange and electrostatic adsorption played the main role for the phosphorus removal from water using the composite adsorbent.

Efficiency of phosphorus removal and recovery from wastewater using marl and travertine and their thermally treated forms

This paper presents a study under the dynamic conditions of marl and travertine materials and their thermal modifications (heated in a muffle furnace for 1 h: marl at 1000 °C, and travertine at 700 °C) and the material Polonite® in terms of phosphorus binding from municipal wastewater. The tests were carried out in filtration columns using hydraulic loads of 118.13, 312.56, and 640.45 dm3/(m2·h) until the ratio of effluent phosphorus concentration to initial phosphorus concentration reached 0.97. Materials with adsorbed phosphorus were subjected to the desorption process using distilled water and NaOH and HCl solutions, applying a hydraulic load of 312.56 dm3/(m2·h). To comprehensively assess the potential use of materials and their thermal modification in agriculture, leaching of elements from them was determined. The most favorable hydraulic load was 118.13 dm3/(m2·h), at which the sorbents achieved the best efficiency. The marl heated at 1000 °C was the most effective, achieving the longest working time of the bed with an efficiency greater than 98 %. The best reagent for desorbing phosphorus from the heated marl surface was a solution of 0.1 mol/L HCl, while for other materials a solution of NaOH 0.1 mol/L. Raw marl was the best at releasing phosphorus in the presence of distilled water, which combined with the results for the leaching of elements from this sorbent, indicate its potential use as a fertilizer or soil conditioner in agricultural production.

Effects of Regional Climate and BMP Type on Stormwater Nutrient Concentrations in BMPs: A Meta-Analysis.

Nutrient treatment performance of stormwater best management practices (BMPs) is highly variable. Improved nutrient management with BMPs requires a better understanding of factors that influence stormwater BMP treatment processes. We conducted a meta-analysis of vegetated BMPs in the International Stormwater BMP Database and compared influent and effluent nitrogen and phosphorus concentrations to quantify the BMP effect on nutrient management across climates. BMP effect on nutrient concentration change was compared between vegetated BMPs in wet and dry climates. We examined paired dissolved inorganic nitrogen (DIN), total nitrogen (TN), dissolved inorganic phosphorus (DIP), total phosphorus (TP), and combinations of these analytes as dissolved inorganic ratios and N:P ratios. Meta-analysis with subgroup analysis was used to determine differences between wet and dry climates and among vegetated BMP types. We found that across both wet and dry climates, BMPs leach DIP and TP, increase the fraction of dissolved inorganic P (DIP:TP), and decrease dissolved N:P ratios. Dry-climate BMPs leach DIP and TP more consistently and at a higher magnitude than wet-climate BMPs, and bioretention leaches more DIP than grass strips and swales. These findings generally align with biogeochemical cycling, differences in influent chemistry, and BMP design types and goals.

Operational optimization at the Nenäinniemi wastewater treatment plant's tertiary disc filter phosphorus removal installation to reduce chemical consumption.

Instrumentation, automation and control in municipal wastewater treatment can result in large resource, cost and energy savings. Feedforward and feedback control algorithms were implemented together with turbidity and phosphorus analysers to control the chemical dose at the tertiary stage of the Nenäinniemi wastewater treatment plant, consisting of coagulation, flocculation and microsieve filtration. This optimization lowered the coagulant dose by 70% and the polymer dose by 36% compared to manual adjustments of the chemical dosing. Effluent total phosphorus (TP) and total suspended solids (TSS) concentrations were lowered by 20-30%. With the control system in operation, the annual savings in coagulant and polymer were in the range of 100 and 1.4 tons, respectively. Conducting automated CIP on the media at an economical break-even interval of approximately 20 days was also important to further lower energy usage and operational costs.

Balance nitrogen and phosphorus efficient removal under carbon limitation in pilot-scale demonstration of a novel anaerobic/aerobic/anoxic process

Nutrient removal in carbon limited wastewater with high efficiency and energy saving remains a bottleneck for wastewater treatment plants (WWTPs). This study established a pilot-scale anaerobic/aerobic/anoxic (AOA) system with processing capacity of 100 m3/d for the first time. During almost 300 days of stable operation, enhanced nitrogen and phosphorus removal at a C/N of 5 was achieved, and the concentrations of total nitrogen (TN) and total phosphorus (TP) in effluent were 3.60 ± 1.55 and 0.24 ± 0.13 mg/L. Tetrasphaera and Candidatus Competibacter were the dominant phosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) in the AOA system. Moreover, the low phosphorus release ensured sufficient intracellular carbon storage by endogenous denitrification, which was the critical factor for nitrogen and phosphorus removal in carbon limited wastewater. The denitrification phosphorus removal (DPR) ability further removed phosphorus and prevented secondary phosphorus release to maintain a low phosphorus concentration in effluent. Finally, rapid start-up, high nutrient removal efficiency and low energy consumption make the proposed AOA process suitable for application in newly constructed and renovated WWTPs.

An effective titanium salt dosing strategy for phosphorus removal from wastewater: Synergistic enhancement of chemical and biological treatment

Titanium salt coagulant, as a new type of water treatment agent, has been widely studied, but most researches do not consider its effect on the biological treatment. In this study, different doses of TiCl4 were added to the biological phosphorus removal (BPR) system to investigate the impact of TiCl4 on BPR. The results showed that the addition of TiCl4 not only significantly reduced the phosphorus concentration in effluent (below 0.5 mg/L), but also kept it stable. Moreover, the sedimentation performance of activated sludge was improved, which was superior to the control group. According to the results of flow cytometry (FCM), a small amount of TiCl4 significantly improved the bioactivities, but excessive dosage caused inhibition. When the dosage of TiCl4 below 20 mg/L, polyphosphate accumulating metabolism (PAM) was strengthened. In addition, the richness of microbial community and the relative abundance of Candidatus Accumulibacter clades also increased. However, when the dosage reached 60 mg/L, the relative abundance of Candidatus Competibacter increased and the BPR system was deteriorated. This study suggests that the addition of appropriate concentration of TiCl4 can realize the synergistic enhancement of biological and chemical phosphorus removal in sewage treatment.

Species identity but not richness affects effluent nitrogen, phosphorus, and potassium concentrations and the ratios in floating-constructed wetlands.

The nutrient ratio in wastewater discharge has a variety of ecological impacts on aquatic ecosystems. Plant species richness and identity (the presence of certain species in the community) affected the nitrogen (N), phosphorus (P), and potassium (K) removal efficiencies in constructed wetlands (CWs). However, the effects on the ratios of N/P/K are still unknown. This study conducted microcosms simulating floating CWs to explore the effects on these nutrient removal efficiencies and ratios. Results showed that (1) the presence of Canna indica decreased but the presence of Arundo donax increased effluent P and K concentrations, plant richness had no effect on effluent nutrients concentrations; (2) plant species richness only decreased the effluent P:K ratio but no effect on other effluent nutrient ratios; (3) the presence of C. indica increased but the presence of A. donax decreased effluent N:P and N:K ratios; (4) the presence of C. indica increased plant N, P, K pools through increasing plant biomass but the presence of A. donax decreased plant N, P, K pools through decreasing plant biomass. Overall, species identity surpassed species richness in affecting effluent nutrient concentrations and ratios. Assembling proper species composition could decrease effluent P and K concentrations and regulate effluent N/P/K ratios.

Mainstream partial denitrification-anammox (PD/A) for municipal sewage treatment from moderate to low temperature: Reactor performance and bacterial structure

Anammox is sensitive to temperature, which can limit its practical application in wastewater treatment. In this study, a step-feed anoxic-oxic (A/O) process coupled with PD/A was operated steadily from 26.8 °C to 13.1 °C for wastewater treatment for 200 days. The effluent total inorganic nitrogen (TIN) and phosphorus concentrations were 10.2 mg/L and 0.29 mg/L at C/N ratio of 4.6 and 15.0 °C even with increasing nitrogen loading rate (NLR). The anammox activity was 5.60 mg NH4+-N/gMLSS/d even at 14 °C, moreover, anammox abundance on the biocarriers increased with decreasing temperature. It was observed that the effect of partial denitrification (PD) was enhanced under low temperature, thus the contribution of anammox for nitrogen removal was improved. The pathway of anammox for nitrogen removal accounted for 48% and the effect of effluent did not deteriorate under low temperature. This study states that PD/A has advantages under low temperature operation, which is suitable for treatment of wastewater with low C/N ratio.

Management of the Phosphorus–Cladophora Dynamic at a Site on Lake Ontario Using a Multi-Module Bioavailable P Model

The filamentous green alga Cladophora grows to nuisance proportions in Lake Ontario. Stimulated by high phosphorus concentrations, nuisance growth results in the degradation of beaches and clogging of industrial water intakes with attendant loss of beneficial uses. We develop a multi-module bioavailable phosphorus model to examine the efficacy of phosphorus management strategies in mitigating nuisance algal growth. The model platform includes modules simulating hydrodynamics (FVCOM), phosphorus-phytoplankton dynamics (GEM) and Cladophora growth (GLCMv3). The model is applied along a 25 km stretch of the Lake Ontario nearshore, extending east from Toronto, ON and receiving effluent from three wastewater treatment plants. Simulation results identify the Duffin Creek wastewater treatment plant effluent as a driving force for nuisance conditions of Cladophora growth, as reflected in effluent bioavailable phosphorus concentrations and the dimensions of the plant’s phosphorus footprint. Simulation results demonstrate that phosphorus removal by chemically enhanced secondary treatment is insufficient to provide relief from nuisance conditions. Tertiary treatment (chemically enhanced secondary treatment with ballasted flocculation) is shown to eliminate phosphorus-saturated conditions associated with the Duffin Creek wastewater treatment plant effluent, providing local relief from nuisance conditions. Management guidance presented here has wider application at sites along the highly urbanized Canadian nearshore of Lake Ontario.

Wastewater lagoon solids, phosphorus, and algae removal using discfiltration

Abstract The microsieving discfilter technology was investigated at the pilot scale. The pilot was configured to treat the effluent from a municipal wastewater multi-lagoon facility consisting of two facultative lagoons and a third seasonally aerated lagoon that is aerated to mitigate hydrogen sulfide release. The 10 μm filter, operated without chemical enhancement, demonstrates 60.1 ± 22.6% removal of the lagoon effluent total suspended solids (TSS) during periods of operation without aeration of the third lagoon. Aeration of the third lagoon of the multi-lagoon system prior to discharge renders the 10 μm filter cloth ineffective with respect to solids removal. The 5 μm filter cloth performs effective nonchemically enhanced removal of solids even during aeration of the lagoon, removing 68.2 ± 9.85% of effluent TSS. The greater performance of the 5 μm filter was achieved at the expense of a lower maximum conveyance capacity than the 10 μm filter. The 10 and 5 μm filters decrease the effluent total phosphorus (TP) concentrations by 0.14 and 0.13 mg-P/L, respectively. Algae, characterized as Chlorophyll α, shows removal from influent concentrations of 10.25 ± 4.19 μg/L to concentrations of 4.61 ± 1.28 μg/L for the 10 μm filter, and 4.10 ± 0.65 μg/L for the 5 μm filter.

Membrane fouling suppression using intermittent electric current with low exposure time in a sequencing batch membrane bioreactor

Abstract This study assessed for the first time the use of intermittent electric current with low exposure time in a sequential batch membrane bioreactor (SB-MBR) aiming at reducing the membrane fouling and improving the treatment performance. The SB-MBR was initially operated without electric current application (control period) and, subsequently, using the electric current density of 10 A m−2 and intermittent exposure mode of 6 min ON/30 min OFF (1.2 h d−1). Compared to the control period, the mixed liquor filterability improved substantially when the electrocoagulation was applied, resulting in a membrane fouling rate 65% lower. This better filterability condition was attributed to the improvement of the floc formation process, which resulted in larger floc size and lower sludge volume index. The biomass growth was positively impacted by the electrochemical process, resulting in a higher sludge yield coefficient. The reactor performance regarding COD and NH4+-N removal was not influenced by the electric current application, exhibiting efficiencies above 99% in both experimental periods. On the other hand, the phosphorus concentration in the reactor effluent decreased as the electrocoagulation was applied, increasing its average removal efficiency from 62% (control period) to 89%. The anodic dissolution rate was estimated at 1.28 g d−1, considerably lower than the values reported in other studies regarding EBRM running in continuous mode. Thus, it can be inferred that the integration of the electrochemical process with SB-MBR using low exposure mode is an interesting alterative to reduce the membrane fouling, extend the anode lifespan and improve the reactor performance.

La-based-adsorbents for efficient biological phosphorus treatment of wastewater: Synergistically strengthen of chemical and biological removal

The present work demonstrated the invention of synergistically strengthen of chemical and biological removal of phosphorus (P) in biological wastewater treatment, which was achieved by exposure the bioreactors to different levels of La-based-adsorbents. We fabricated a high-performance La2O2CO3 micro-adsorbent (H–La2O2CO3) and added it into sequencing batch reactors. When activated sludge was exposed to 40 mg/L H–La2O2CO3 for 40 d, effluent total phosphorus (TP) concentration significantly decreased to approximately 0.18 mg/L, with the steady removal efficiency of 96.4%, which is superior to the biological phosphorus removal (BPR). The effect of H–La2O2CO3 dosages on P removal in biological wastewater treatment was also detailedly investigated. The H–La2O2CO3 adsorbent could not only capture P by chemical bonding itself, but also increased protein (PN) contents of extracellular polymeric substances (EPS) and changed the functional group of EPS to chemically adsorb P. Additionally, the results of 16s rDNA molecular analysis revealed that the species richness and microbial diversity varied with the different dosages of adsorbent. Sequence analyses showed that the appropriate concentration of H–La2O2CO3 addition increased the contents of several polyphosphate accumulating organisms (PAOs) at genus level in sludge.